1. Field of the Invention
This invention relates to a device for continuously winding a wire-like element. The invention is particularly well suited for use with an optical fiber.
2. Description of the Prior Art
Devices are known in the art which wind a wire-like element such as an optical fiber. Such devices generally include two bobbins which are wound alternately so as to effect a continuous winding of the wire-like element. FIG. 3 is a schematic view of such a device and FIGS. 4(a)-(i) show the operation of the device of FIG. 3.
Referring to FIG. 3, first and second bobbins 13 and 14 are driven by motors 11 and 12 respectively. The wire-like element 15 is guided by guide roller 16 so that element 15 can be switched between bobbins 13 and 14 on which it is being wound. Each of bobbins 13 and 14 has a catch, device 17 depicted only on bobbin 13 in FIGS. 4(a)-(i) Such a catch device is described in Japanese Patent Publication No. 11825/82.
Referring to FIGS. 4(a)-4(i ) device 17 is made of a guide disc 18 arranged coaxially with bobbins 13 and 14 and rotatable therewith, a catch arm 20 angularly movably supported on the peripheral portion of guide disc 18 and having a catch rubber 19 with a V-shaped groove, a spring 21 urging catch arm 20 to be inwardly retracted, and a cam 22 angularly movably supported on guide disk 18 and engaged with catch arm 20. The catch device is operated at a predetermined timing by cam plate 23 mounted exterior to and adjacent to guide disc 18.
The switching between bobbins 13 and 14 of the above-described device is described below. When the wire-like element is being wound on bobbin 14, guide roller 16 is disposed between bobbins 13 and 14 as is shown in FIGS. 4(a), 4(d) and 4(g)so as to guide the winding toward bobbin 14. The cam plate 23 is disengaged from cam 22 so that catch arm 20 is disposed in its inwardly-retracted position.
When bobbin 14 has been filled, guide roller 16 moves in the direction of bobbin 13, as shown in FIGS. 4(b), 4(e) and 4(h) so as to bring wire-like element 15 into contact with the body of bobbin 13. The cam plate 23 is operated so as to urge cam 22 causing catch arm 20 to project inside of bobbin 13 against the bias of spring 21. During the rotation of the catch arm 20, catch rubber 19 catches the wire-like element 15 in its V-shaped groove and cuts it.
Then, as shown in FIGS. 4(c), 4(f) and 4(i) cam plate 23 is released to retract catch arm 20, thus completing the switching of the wire-like element 15 to bobbin 13. When it is desireable to switch in the reverse order, that is from bobbin 13 to 14, the catch device 17 on bobbin 14 (not shown) is responsible for carrying out the switching operation.
The cam plate 23 of the device described above is driven by a solenoid through a link 25 as shown in FIG. 5. The timing of the movement of cam plate 23 is detected through the bobbin shaft. The solenoid 24 is operated in response to a signal from a sequencer of a controller.
Cam plate 23 must be operated when catch device 17 is located at a success zone shown in FIG. 6. If cam plate 23 is operated when catch device 17 is located in a failure zone immediately before a catch point P where catch device 17 can catch wire-like element 15, catch arm 20 is projected in an incomplete condition. When this occurs, the V-shaped groove of a catch rubber 19 does not catch element 15, therefore resulting in a failure to switch the winding. A timing pulse is therefore generated when the bobbin shaft is at a predetermined angular position, and this timing pulse operates the solenoid 24 at a predetermined time.
Even when a timing pulse is generated at a predetermined time, variations arise in a scan time of a sequencer and thus the operation of solenoid 24. The timing of the operation of the cam plate 23 is subject to a variation time interval of length T.sub.o.
If the time during which catch device 17 is disposed in the success zone extending over an angle of Y.degree. is called S.sub.o , it can be found that:
S.sub.o =(time per revolution of bobbin) = x When the bobbin rotates at a low rate of speed, the cam plate 23 can be successfully operated during the interval S.sub.o regardless of the interval T.sub.o since S.sub.o is sufficiently long compared to time T.sub.o as shown in FIG. 7. However, when the bobbin rotates at a high rate of speed, time S.sub.o becomes smaller as depicted in FIG. 8. When S.sub.o is sufficiently short compared to T.sub.o , proper operation of catch device 17 becomes difficult. Due to both electrical and mechanical factors, a variation time T.sub.o is inherent in this system as are the problems at high bobbin rotation speeds.